The present invention relates to new piperidine compounds which are useful as therapeutic drugs for circulatory diseases such as hypertension and congestive heart failure, or isomers thereof as well as pharmaceutically acceptable salts thereof and the intermediates for their synthesis.
There have been reported a wide variety of hypotensive drugs whose mode of action is based on the inhibition of angiotensin-converting enzyme [Drugs of the Future, vol. 8, p. 1051 (1983)]. The representative examples thereof include oligopeptide compounds such as captopril (U.S. Pat. No. 4,046,889) and enalapril (European Patent Application No. 12401A). In addition, it has recently been found that nonpeptide compounds such as benzazepine derivatives or benzothiazepine compounds have a similar hypotensive effect (European Patent Application Nos. 72,352A and 156,455A, and Japanese Patent Application Publication (Unexamined) No. 148171/1986).
These hypotensive drugs are not always satisfactory in respect of effect certainty, action prolongation or adverse reaction, despite the fact that their dosing usually continues for a long period.
The present inventors made investigations to solve these problems; as a result, the inventors found that piperidine compounds or isomers thereof as well as salt and/or hydrate forms thereof inhibit an angiotensin-converting enzyme, and exhibit long lasting and excellent hypotensive activity, and completed this invention.